As is known, heat, oxygen and light, especially the actinic radiations existing in the low wave-length ultraviolet band, do badly affect the appearance and the properties of the organic polymers. For example, the polyesters, which are usually colorless, yellow when exposed to sunlight. Analogously, the oxidizing rate of polyolefins when exposed to air is highly increased due to ultraviolet light; polystyrene gets yellow and brittle, with corresponding loss of its desirable properties, when exposed to actinic light, etc. The same degradation and alteration effects of the mechanical properties occur when the polymeric materials are subjected to heat-treatments, as happens for example during their transformation into formed articles, such as films, fibers and the like.
With a view to stabilizing the polymeric materials and to retaining unaltered the properties thereof, it is a usual practice to add to them one or more stabilizers, the function of which is just that of opposing the susceptibility of such materials of undergoing an oxidative and thermal degradation.
A particular type of stabilizers which has been very successful are the stereically hindered amines (HALS) and in particular the derivatives of alkyl-substituted piperidine.
The hingered amines based on alkyl-substituted piperidine, though being excellent stabilizers for polymeric substances generally subject to worsening, are not suited to be utilized, with the same results, in all polymeric substances and for all technological uses. In fact, the known stabilizers are affected by the drawback of not possessing all those parameters and technical characteristics necessary for all the technological applications, such as low volatility, resistance to migration, thermal stability, insolubility in water, etc.
Thus, it is an object of the present invention to improve the properties of the known stabilizers containing the radical of alkyl-substituted piperidine.
It has now been found that this and still further objects are achieved by derivatives of alkyl-substituted 4-hydroxy-methyl-piperidine having general formula: ##STR3## in which: R.sub.1, R.sub.2, R.sub.3 and R.sub.4, which may be like or unlike one another, are each a lower alkyl group, or R.sub.1 and R.sub.2 and/or R.sub.3 and R.sub.4, along with a carbon atom which they are bound to, represent a cyclo-alkyl group or a group of formula: ##STR4## in which R.sub.6, R.sub.7, R.sub.8 and R.sub.9, which may be like or unlike one another, are a hydrogen atom or a lower alkyl group and R.sub.5 has the meaning specified hereinbelow;
R.sub.5 is a hydrogen atom, an alkyl group, an alkenyl group, an alkoxyalkyl group, an aralkyl group, either non-substituted or carrying one or more substituents on the aryl radical, a 2,3-epoxypropyl group, a group of formula --CH.sub.2 --COOR.sub.10 (in which R.sub.10 is an alkyl group, an alkenyl group, an aralkyl group or a cyclohexyl group), a group of formula: ##STR5## (in which R.sub.11 is a hydrogen atom, a methyl group, an ethyl group or a phenyl group and R.sub.12 is a hydrogen atom, an alkyl-substituted piperidyl group, a triazinyl group or an acyl group), an aliphatic acyl group or a group of formula --COOR.sub.13 (in which R.sub.13 is an alkyl group, a benzyl group or a phenyl group); PA1 Y represents an organic or inorganic group or atom having a valence of from 1 to 4 which does not adversely affect the stabilizing activity of the polymer; and PA1 n is an integer from 1 to 4, depending on the valence of Y. PA1 an alkyl group containing preferably from 1 to 18 carbon atoms, such as methyl, ethyl, isopropyl, butyl, isobutyl, t.butyl, isopentyl, octyl, dodecyl, octadecyl, etc.; PA1 an alkenyl group preferably containing from 3 to 6 carbon atoms, such as allyl, 2-butenyl, 2-hexyl, etc.; PA1 a phenyl group; PA1 an aralkyl group, preferably containing 7 or 8 carbon atoms, or PA1 a cyclohexyl group; the alkyl group containing 1 to 4 carbon atoms being the preferred one. PA1 a hydrogen atom; PA1 an acyl-aliphatic, aryl-aliphatic, alicyclic, aromatic or heterocyclic group, preferably an acyl group containing up to 18 carbon atoms and, even better, a group of formula --COR.sub.19 in which R.sub.19 represents a hydrogen atom; an alkyl group with 1 to 17 carbon atoms (such as methyl, ethyl, propyl, isopropyl, butyl, ter.butyl, pentyl, isopentyl, 1-ethylpentyl, nonyl, undecyl, pentadecyl, etc.); an alkenyl group with 2 to 5 carbon atoms, such as vinyl, 1-propenyl, 2-methyl-1-propenyl, isopropenyl, or 1,3-pentadienyl; an alkynyl group with 2 or 3 carbon atoms, such as ethynyl or propynyl; a phenyl group either non-substituted or substituted with up to 3 substituents either like or unlike, such as chlorine, alkyl with 1 to 4 carbon atoms, alkoxy with 1 to 8 carbon atoms, hydroxy or nitro (such as for example phenyl, o.chlorophenyl, m.chlorophenyl, p.chlorophenyl, o.methylphenyl, m.methylphenyl, p.methylphenyl, p.isopropylphenyl, p.ter.butylphenyl, m.methoxyphenyl, p.methoxyphenyl, p.octoxyphenyl, o.hydroxyphenyl, 2-hydroxy-3-methylphenyl, 4-hydroxy-3,5-di-ter.butylphenyl, m.nitrophenyl, etc.); a naphthyl group; a styryl group; an aralkyl group with 7-8 carbon atoms, which may be non-substituted or substituted with up to 3 like or unlike substituents such as chlorine, alkyl with 1-4 carbon atoms, alkoxy with 1 to 8 carbon atoms or hydroxy (such as benzyl, phenethyl, 4-hydroxy-3,5-di-ter.butylbenzyl or 4-hydroxy-3,5-di-ter.butylphenethyl); a phenoxymethyl group; a cyclohexyl group; a 2-pyridyl group; a 3pyridyl group; a 4-pyridyl group; a 2-furyl group; PA1 a group of formula --CO--R.sub.20 --COOH, in which R.sub.20 is an alkylene group preferably containing from 1 to 10 carbon atoms, the chain of which can be interrupted by an atom of oxygen or of sulphur; or a metal salt thereof in which the metal may be, for example, barium, nickel, manganese, calcium, zinc, iron, sodium, cobalt or tin; or a lower alkyl ester thereof in which the alkyl chain contains from 1 to 4 carbon atoms, such as the methyl, ethyl, propyl, butyl esters, etc.; PA1 a radical obtained from the removal of a hydroxy group of a phosphorus acid, for example a radical of phosphoric acid, of phosphonic acid, or phosphorous acid, either simple or substituted such as the radicals ##STR12## a group of formula: ##STR13## in which R.sub.21 is hydrogen; an alkyl group containing 1 to 4 carbon atoms; an aralkyl group preferably containing 7 or 8 carbon atoms; a phenyl group; and R.sub.22 is an alkyl group containing from 1 to 18 carbon atoms, an aryl group preferably containing 6 to 10 carbon atoms, optionally substituted by one or more chlorine atoms and/or alkyl groups with from 1 to 4 carbon atoms, such as for example phenyl, o.chlorophenyl, p.chlorophenyl, o., m. and p.toluyl, alpha-naphthyl or beta-naphthyl; an aralkyl group containing 7 or 8 carbon atoms, or a cyclohexyl group. As an alternative, R.sub.21 and R.sub.22, together and with the nitrogen atom to which they are bound, represent a piperidine group, a 1-pyrrolidinyl group or a morpholine group. Among these groups, those having formula --CO--NH--R.sub.22, in which R.sub.22 is the same as specified hereinbefore, are particularly preferred; PA1 an alkyl group preferably containing from 1 to 18 carbon atoms, such as methyl, ethyl, butyl, octyl, dodecyl or octadecyl; PA1 an alkynyl group preferably containing from 3 to 6 carbon atoms, such as allyl, 2-butenyl, methallyl or 2-hexenyl; PA1 an aralkyl group with from 7 to 9 carbon atoms and optionally carrying up to 3 substituents in the aryl chain, such as an alkyl with from 1 to 4 carbon atoms and/or a hydroxy, such as for example benzyl, p.methylbenzyl, p.isopropylbenzyl; 4-hydroxy-3,5-di-ter.butylbenzyl or 3-(4-hydroxy-3,5-di-ter.butylphenyl)-propyl; PA1 a cyclohexyl group; PA1 a group of formula ##STR14## in which R.sub.23 is a hydrogen atom, a methyl or lower alkyl group or a phenyl group and R.sub.24 an alkyl group containing preferably from 1 to 8 carbon atoms. PA1 an aliphatic, araliphatic, aromatic, alicyclic or heterocyclic diacyl, preferably containing up to 12 carbon atoms and, preferably a group of formula --CO--(R.sub.25).sub.m --CO-- in which m may be 0 or 1 and R.sub.25 an alkylene group with 1 to 20 carbon atoms either linear or ramified, optionally containing the alkylbenzyl or hydroxy-alkylbenzyl group, and the chain of which may be interrupted by an atom of sulphur or of oxygen; an alkylene group with from 2 to 4 carbon atoms; a phenylene group, a cyclohexylene group; a 2-4-pyridindiyl group, a 2,5-pyridindiyl group or a thiophendiyl group; PA1 a carbonyl group; PA1 a group obtained by removing the two hydroxyl groups of an acid containing phosphorus, in particular a group of formula: ##STR15## in which R.sub.26 represents a hydrogen atom; an alkyl group with preferably from 1 to 4 carbon atoms; a phenyl or benzyl group, optionally substituted, such as 4-hydroxy-3,5-di-tertbutylbenzyl; PA1 a group of formula: ##STR16## a group of formula: ##STR17## in which R.sub.21 is the same as indicated hereinabove and R.sub.27 represents an alkylene group preferably containing from 2 to 10 carbon atoms; an arylene group having preferably from 6 to 10 carbon atoms and optionally substituted such as o.phenylene, m.phenylene, p.phenylene, 2,4-toluidene, 1,5-naphthylene, etc., a xylylene group, a cyclohexylene group such as 1,4-cyclohexylene, PA1 a group of formula: ##STR18## in which R.sub.28 may be an oxygen atom of an alkylene group containing from 1 to 4 carbon atoms; PA1 a group of formula: ##STR19## in which R.sub.29 may be a hydrogen atom of a methyl group, a group of formula: ##STR20## such as methylene-di-4,1-cyclohexene, or a group of formula: ##STR21## such as for example 1,3-cyclohexylene-dimethylene, etc.; among the groups comprised in this formula, those of formula --CO--NH--R.sub.27 --NH--CO--, in which R.sub.27 has the values defined hereinbefore, are the preferred; PA1 an alkylene group containing up to 10 carbon atoms and preferably from 2 to 6 carbon atoms, such as ethylene, tetramethylene, hexamethylene, etc.; PA1 an alkenylene group containing from 4 to 10 carbon atoms; PA1 or PA1 a xylylene group, such as o.xylylene, m.xylylene, p.xylylene, etc. PA1 polymers of olefins and of dienes, such as: homopolymers of olefins and of dienes (e.g., low density polyethylene, high density polyethylene and cross-linked polyethylene, polypropylene, polyisobutene, polymethylbutene-1, polymethylpentene-1, polyisoprene, polybutadiene), mixtures of such homopolymers or copolymers (for example, ethylene-propylene copolymers, propylene-butene-1 copolymers, or ethylene-propylene terpolymers and dienes, such as hexadiene, dicyclopentadiene), etc.; PA1 styrene polymers, such as: polystyrene, copolymers of styrene and .alpha.-methylstyrene with acrylonitrile, methyl methacrylate, acrylic esters, styrene polymers modified with elastomers, grafted styrene polymers, etc.; PA1 halogenated vinyl and vinylidene polymers, such as: vinyl polychloride, vinylidene polychloride, vinyl polyfluoride, polychloroprene, vinyl chloride/vinylidene chloride copolymers, vinyl chloride/vinyl acetate copolymers, vinylidene chloride/vinyl acetate copolymers, etc.; PA1 polymers deriving from .alpha.-.beta.-unsaturated acids, such as: polyacrylates, polymethacrylates, polyacrylonitrile, polyacrylic amides; PA1 polymers deriving from alcohols and from unsaturated amines and acylated or acetal derivatives thereof, such as polyvinyl alcohol, polyvinyl acetate, polyallyl melamine and copolymers thereof with other ethylenically unsaturated monomers; PA1 epoxide polymers; PA1 polyacetals; PA1 polyurethanes and polyureas; PA1 polycarbamates; PA1 polysulphones; PA1 polyamides and copolyamides; PA1 polyesters; PA1 cross-linked polymers, deriving from aldehydes and from phenols, from ureas or from melamines; PA1 alkyd resins; PA1 unsaturated polyester resins; PA1 natural polymers, such as cellulose, rubber, proteins or chemically modified analogues thereof (e.g., cellulose acetate), etc.
According to the present invention it has been also found that the derivatives of alkyl-substituted 4-hydroxy-methyl-piperidine having general formula (I), either alone or in admixture with other known stabilizers, can efficaciously stabilize a wide range of polymers against photo and thermal degradation and, furthermore, they are highly compatible with the polymers, in particular with polyolefins.
The term "lower alkyl", whenever used herein and in the annexed claims, means an alkyl containing from 1 to 6 carbon atoms, extremes included.
In above-reported formula (I), when R.sub.1, R.sub.2, R.sub.3 or R.sub.4 represents an alkyl group, this may be preferably an alkyl group containing from 1 to 4 carbon atoms, such as, e.g., methyl, ethyl, propyl, isopropyl, butyl or isobutyl, the methyl group being preferred.
R.sub.1 and R.sub.2 and/or R.sub.3 and R.sub.4, along with the carbon atom on which they are bound, may represent a cycloalkyl group containing from 5 to 7 carbon atoms, such as, e.g., cyclopentyl, cyclohexyl, cycloheptyl, etc., or an alkyl-substituted piperidyl group, such as for example: ##STR6##
When R.sub.5 is an alkyl group, it may contain from 1 to 8 carbon atoms. In practice, it is preferable that the alkyl group contain from 1 to 4 carbon atoms and among these, the methyl group is particularly preferred.
When R.sub.5 is an alkenyl group, it may contain from 3 to 6 carbon atoms, such as e.g., the allyl group, the 2-butenyl group or the 2-hexenyl group; the alkenyl group containing 3 or 4 carbon atoms is the preferred one, and among said groups the allyl group is particularly preferred.
When R.sub.5 is an alkoxyalkyl group, it may be an alkoxyalkyl group containing 1 to 3 carbon atoms in the alkyl chain and from 1 to 18 carbon atoms in the alkoxyl chain.
Examples of alkoxyalkyl groups are: methoxymethyl, ethoxymethyl, 2-butoxyethyl, 3-butoxypropyl, 2-octoxyethyl, 2-octadecyloxyethyl. Of the alkoxy-alkyl groups, those containing on the whole 2 to 6 carbo-atoms are preferred.
When R.sub.5 is an aralkyl group, it may preferably contain 7 or 8 carbon atoms and it may be unsubstituted or it may contain up to 3 substituents on the alkyl radical. Chlorine atoms, alkyl groups with 1 to 4 carbon atoms, alkoxy groups with 1 to 8 carbon atoms or hydroxy groups may be used as substituents. Typical examples of aralkyl groups are: benzyl, p.chlorobenzyl o.chlorobenzyl, m.chlorobenzyl, o.methylbenzyl, m.methylbenzyl, p.methylbenzyl, p.isopropylbenzyl, p.ter.butylbenzyl, p.methoxybenzyl, p.butoxybenzyl, p.octoxybenzyl, 4-hydroxy-3,5-di-ter. butylbenzyl, etc.
When R.sub.5 represents a group of formula --CH.sub.2 --COOR.sub.10, R.sub.10 may represent:
When R.sub.5 represents the group ##STR7## R.sub.11 represents a hydrogen atom, a methyl group or a phenyl group and R.sub.12 represents a hydrogen atom, an acyl group, for example an acyl aliphatic, araliphatic, aromatic or alicyclic group, an alkyl-substituted piperidyl group, such as: ##STR8## or a triazinic group, such as: ##STR9## in which Z and Z', which may be like or unlike each other, represent hydrogen, --NR.sub.14 R.sub.15, --O--R.sub.16 or --S--R.sub.17 in which R.sub.14, R.sub.15, R.sub.16 and R.sub.17 may be hydrogen, an alkyl radical containing from 1 to 18 carbon atoms or an alkyl-substituted piperidyl group such as: ##STR10## or R.sub.14 and R.sub.15 along with the N atom form together a cycle either or not containing other heteroatoms such as: ##STR11##
When R.sub.12 is an acyl group, this has preferably the formula --COR.sub.18 in which R.sub.18 is an alkyl group with 1 to 18 carbon atoms; an alkenyl group with from 2 to 4 carbon atoms; a phenyl group, which may be either non-substituted or substituted with up to 3 substituents, equal or different, selected from among chlorine, alkyl with 1 to 4 carbon atoms, alkoxy with 1 to 8 carbon atoms or hydroxy; an aralkyl group with 7 or 8 carbon atoms, the aryl radical of which may be non-substituted or substituted with up to 3 substituents, like or different from one another, selected from among chlorine, alkyl with 1 to 4 carbon atoms, alkoxy with 1 to 6 carbon atoms or hydroxy; a styryl group, or a cyclohexyl group.
Examples of radicals R.sub.18 are: methyl, ethyl, propyl, butyl, heptyl, 1-ethyl-pentyl, nonyl, undecyl, heptadecyl, vinyl, 1-propenyl, 2-methyl-1-propenyl, 1-butenyl, phenyl, o.chlorophenyl, m.chlorophenyl, 2,4-di-chlorophenyl, o.methylphenyl, p.methylphenyl, m.methylphenyl, p.isopropylphenyl, p.ter.butylphenyl, p.methoxyphenyl, p.ethoxyphenyl, p.butoxyphenyl, 3,4,5-trimethoxyphenyl, o.hydroxyphenyl, 4-hydroxy-3,5-di-ter. butylphenyl, benzyl, p.methylbenzyl, 4-hydroxy-3,5-di-ter. butylphenyl.
Particularly preferred are the groups of formula --CH.sub.2 --CH.sub.2 --O--R.sub.12, in which R.sub.12 has one of the values cited hereinbefore.
When R.sub.5 is an aliphatic acyl group, it may preferably contain up to 4 carbon atoms and it is preferably a saturated or unsaturated acyl group, such as e.g., the formyl, acetyl, acrylyl or crotonyl groups.
When R.sub.5 is a group of formula --COOR.sub.13, R.sub.13 is an alkyl group, preferably with 1 to 8 carbon atoms, such as methyl, ethyl, isobutyl, heptyl; a benzyl group or a phenyl group.
Generally speaking, group Y represents a hydrogen atom, a hydrocarbon residue which may be non-substituted or substituted, a residue deriving from an organic or inorganic acid, a heterocyclic group, an atom of phosphorus or of boron or of silicon. In particular, the following groups are the preferred ones:
When n=1
Y preferably represents:
When n=2
Y represents:
When n=3
Y may be selected from the following radicals: ##STR22##
When n=4
Y may be: ##STR23##
The derivatives of the alkyl-substituted 4-hydroxy-piperidine which are particularly preferred are those of general formula: ##STR24## in which R.sub.5 is a hydrogen atom, a methyl group, a benzyl group, a 2,3-opoxypropyl group or a group of formula --CH.sub.2 --CH.sub.2 --O--R.sub.12, in which R.sub.12 is hydrogen or an alkyl group with from 2 to 18 carbon atoms or a benzoyl group; n=1, 2 or 3; and
when n=1
Y represents a group of formula --CO--R.sub.19 in which R.sub.19 represents an alkyl group with from 1 to 17 carbon atoms, a phenyl group optionally substituted by up to 3 alkyl radicals with from 1 to 4 carbon atoms and/or a hydroxy radical, or a 4-hydroxy-3,5-ditert.butylphenethyl; or a group of formula --CO--NH--R.sub.22 in which R.sub.22 represents an alkyl group with from 1 to 18 carbon atoms, a phenyl group or a cyclohexyl group;
when n=2
Y represents a group of formula --CO--(R.sub.25).sub.m --CO-- in which m is 0 or 1 and R.sub.27 represents an alkenyl group with 1 to 10 carbon atoms, the group --CH.sub.2 --CH.sub.2 --S--CH.sub.2 --CH.sub.2 or a phenylene group, a group of formula ##STR25## in which R.sub.27 represents the hexamethylene radical, the 2,4-toluilene radical or the methylene-di-p.phenylene radical;
when n=3
Y represents ##STR26##
The particularly preferred compounds are those in which n=1 and Y represents a group of formula --CO--R.sub.19 ; or n=2 and Y represents a group of formula --CO--R.sub.25 --CO--, with R.sub.19 and R.sub.25 having the values defined hereinbefore.
A non-limitative list of derivatives of alkyl-substituted 4-hydroxy-methyl-piperidine is given hereinbelow, and the numbers which refer to the products will be utilized to identify them also in the examples.
(1) (2,2,6,6-tetramethyl)-4-hydroxymethyl piperidine; PA0 (2) (2,2,6,6-tetramethyl)-4-methyl piperidine acetate; PA0 (3) (2,2,6,6-tetramethyl)-4-methyl piperidine palmitate; PA0 (4) (2,2,6,6-tetramethyl)-4-methyl piperidine ethylhexanoate; PA0 (5) (2,2,6,6-tetramethyl)-4-methyl piperidine stearate; PA0 (6) (2,2,6,6-tetramethyl)-4-methyl piperidine acrylate; PA0 (7) (2,2,6,6-tetramethyl)-4-methyl piperidine crotonate; PA0 (8) (2,2,6,6-tetramethyl)-4-methyl piperidine methacrylate; PA0 (9) (2,2,6,6-tetramethyl)-4-methyl piperidine tetrolate; PA0 (10) (2,2,6,6-tetramethyl)-4-methyl piperidine benzoate; PA0 (11) (2,2,6,6-tetramethyl)-4-methyl piperidine p.tert.butylbenzoate; PA0 (12) (2,2,6,6-tetramethyl)-4-methyl piperidine p-methoxybenzoate; PA0 (13) (2,2,6,6-tetramethyl)-4-methyl piperidine salicylate; PA0 (14) (2,2,6,6-tetramethyl)-4-methyl piperidine p.chlorobenzoate; PA0 (15) (2,2,6,6-tetramethyl)-4-methyl piperidine naphthalene-1-carboxylate; PA0 (16) (2,2,6,6-tetramethyl)-4-methyl piperidine phenyl acetate; PA0 (17) (2,2,6,6-tetramethyl)-4-methyl piperidine .beta.-(4-hydroxy-3,5-ditertbutylphenyl)-propionate; PA0 (18) (2,2,6,6-tetramethyl)-4-methyl piperidine cinnamate; PA0 (19) (2,2,6,6-tetramethyl)-4-methyl piperidine cyclohexancarboxylate; PA0 (20) (2,2,6,6-tetramethyl)-4-methyl piperidine methyl salicylate; PA0 (21) (2,2,6,6-tetramethyl)-4-methyl piperidine methylphthalate; PA0 (22) (1,2,2,6,6-pentamethyl)-4-hydroxymethyl piperidine; PA0 (23) (1,2,2,6,6-pentamethyl)-4-methyl-piperidine stearate; PA0 (24) (1,2,2,6,6-pentamethyl)-4-methyl piperidine benzoate; PA0 (25) (1,2,2,6,6-pentamethyl)-4-methyl piperidine m.toluate; PA0 (26) (1,2,2,6,6-pentamethyl)-4-methyl piperidine p.octyloxybenzoate; PA0 (27) (1,2,2,6,6-pentamethyl)-4-methyl piperidine .beta.-(4-hydroxy-3,5-di-tertbutylphenyl)propionate; PA0 (28) (1-butyl-2,2,6,6-tetramethyl)-4-methyl piperidine hexanoate; PA0 (29) (1-allyl-2,2,6,6-tetramethyl)-4-methyl piperidine stearate; PA0 (30) (1,allyl-2,2,6,6-tetramethyl)-4-methyl piperidine crotonate; PA0 (31) (1-allyl-2,2,6,6-tetramethyl)-4-methyl piperidine benzoate; PA0 (32) (1-benzyl-2,2,6,6-tetramethyl)-4-methyl piperidine acetate; PA0 (33) (1-benzyl-2,2,6,6-tetramethyl)-4-methyl piperidine stearate; PA0 (34) (1-benzyl-2,2,6,6-tetramethyl)-4-methyl piperidine crotonate; PA0 (35) (1-benzyl-2,2,6,6-tetramethyl)-4-methyl piperidine benzoate; PA0 (36) [1(2,3-epoxypropyl)2,2,6,6-tetramethyl]-4-methyl piperidine stearate; PA0 (37) [1(2,3-epoxypropyl)2,2,6,6-tetramethyl]-4-methyl piperidine benzoate; PA0 (38) 1-(2-hydroxyethyl)2,2,6,6-tetramethyl-4-hydroxy methyl piperidine; PA0 (39) [1(2-hydroxyethyl)2,2,6,6-tetramethyl]-4-methyl piperidine benzoate; PA0 (40) [1(2-hydroxypropyl)2,2,6,6-tetramethyl]-4-methyl piperidine benzoate; PA0 (41) 1(2-hydroxy-2-phenylethyl)2,2,6,6-tetramethyl-4-methyl piperidine p.tertbutylbenzoate; PA0 (42) [1(2-acetoxymethyl)2,2,6,6-tetramethyl]-4-methyl piperidine benzoate; PA0 (43) [1(2-stearoyloxyethyl)2,2,6,6-tetramethyl]-4-methyl piperidine stearate; PA0 (44) 1-{2[.beta.-(4-hydroxy-3,5-ditertbutylphenyl)propionyloxy]ethyl}2,2,6,6-te tramethyl-4-methyl piperidine .beta.(4-hydroxy-3,5-di-tertbutyl phenyl)propionate; PA0 (45) [1-(2-palmitoxyethyl)-2,2,6,6-tetramethyl]-4-methyl piperidine palmitate; PA0 (46) [1-2-acetoxypropyl)-2,2,6,6-tetramethyl]-4-methyl piperidine benzoate; PA0 (47) [1-(2-acetoxy-2-phenylethyl)-2,2,6,6-tetramethyl]-4-methyl piperidine butyrate; PA0 (48) (1-ethoxymethyl-2,2,6,6-tetramethyl)-4-methyl piperidine benzoate; PA0 (49) (1-butoxyethyl-2,2,6,6-tetramethyl)-4-methyl piperidine butyrate; PA0 (50) (1-formyl-2,2,6,6-tetramethyl)-4-methyl piperidine butyrate; PA0 (51) (1-acetyl-2,2,6,6-tetramethyl)-4-methyl piperidine benzoate; PA0 (52) (2,2,6,6-tetramethyl)-4-methyl piperidine methyl carbamate; PA0 (53) (2,2,6,6-tetramethyl)-4-methyl piperidine octadecyl carbamate; PA0 (54) (2,2,6,6-tetramethyl)-4-methyl piperidine carbanilate; PA0 (55) (2,2,6,6-tetramethyl)-4-methyl piperidine p.chlorocarbanilate; PA0 (56) (2,2,6,6-tetramethyl)-4-methyl piperidine 1-naphthalene carbamate; PA0 (57) (2,2,6,6-tetramethyl)-4-methyl piperidine cyclohexane carbamate; PA0 (58) (2,2,6,6-tetramethyl)-4-methyl piperidine piperidin-1-carboxylate; PA0 (59) (2,2,6,6-tetramethyl)-4-methyl piperidine pyrrolidin-1-carboxylate; PA0 (60) (1,2,2,6,6-pentamethyl)-4-methyl piperidine methylcarbamate; PA0 (61) (1,2,2,6,6-pentamethyl)-4-methyl piperidine carbanilate; PA0 (62) (1-butyl 2,2,6,6-tetramethyl)-4-methyl piperidine methyl carbamate; PA0 (63) (1-benzyl 2,2,6,6-tetramethyl)-4-methyl piperidine methyl carbamate; PA0 (64) [1-(2-hydroxyethyl)-2,2,6,6-tetramethyl]-4-methyl piperidine cyclohexane carbamate; PA0 (65) [1-(2-acetonyl ethyl)-2,2,6,6-tetramethyl]-4-methyl piperidine methyl carbamate; PA0 (66) (2,2,6,6-tetramethyl)-4-methoxymethyl piperidine; PA0 (67) 4-butoxymethyl-(2,2,6,6-tetramethyl) piperidine; PA0 (68) 4-octadecyloxymethyl-(2,2,6,6-tetramethyl) piperidine; PA0 (69) [(2,2,6,6-tetramethyl-4-hydroxy)-4-piperidine methoxy](2,2,6,6-tetramethyl)-4-methylpiperidine; PA0 (70) .beta.[(2,2,6,6-tetramethyl)-4-piperidine methoxy]ethyl acrylate; PA0 (71) (1,2,2,6,6-pentamethyl)-4-methoxymethyl piperidine; PA0 (72) 4-benzyloxymethyl-(1,2,2,6,6-pentamethyl)piperidine; PA0 (73) 1-allyl2,2,6,6-tetramethyl-4-allyloxymethyl piperidine; PA0 (74) 1-(2-hydroxymethyl)-4-methoxymethyl(2,2,6,6-tetramethyl)piperidine; PA0 (75) 1-(2-acetoxyethyl)-4-methoxymethyl(2,2,6,6-tetramethyl)piperidine; PA0 (76) bis-(2,2,6,6-tetramethyl)-4-methyl piperidine carbonate; PA0 (77) bis-(2,2,6,6-tetramethyl)-4-methyl piperidine oxalate; PA0 (78) bis-(2,2,6,6-tetramethyl)-4-methyl piperidine succinate; PA0 (79) bis-(2,2,6,6-tetramethyl)-4-methyl piperidine adipate; PA0 (80) bis-(2,2,6,6-tetramethyl)-4-methyl piperidine sebacate; PA0 (81) bis-(2,2,6,6-tetramethyl)-4-methyl piperidine (3,5-di-tertbutyl-4-hydroxy)benzyl, n.butyl malonate; PA0 (82) bis-(2,2,6,6-tetramethyl)-4-methyl piperidine diethyl malonate; PA0 (83) bis-(2,4,6,6-tetramethyl)-4-methyl piperidine fumarate PA0 (84) bis-(2,2,6,6-tetramethyl)-4-methyl piperidine terephthalate; PA0 (85) bis-(2,2,6,6-tetramethyl)-4-methyl piperidine cyclohexane 1,4-dicarboxylate; PA0 (86) bis-(2,2,6,6-tetramethyl)-4-methyl piperidine phenyl phosphonate; PA0 (87) bis-(1,2,2,6,6-pentamethyl)-4-methyl piperidine adipate; PA0 (88) bis-(1,2,2,6,6-pentamethyl)-4-methyl piperidine sebacate; PA0 (89) bis-(1,2,2,6,6-pentamethyl)-4-methyl piperidine terephthalate; PA0 (90) mono-(1,2,2,6,6-pentamethyl)-4-methyl piperidine succinate; PA0 (91) mono-(1,2,2,6,6-pentamethyl)-4-methyl piperidine 3,4,5,6-tetrahydrophthalate; PA0 (92) mono-(2,2,6,6-tetramethyl)-4-methyl piperidine maleate; PA0 (93) nickel di-[3,4,5,6-tetrahydrophthalate of mono-(1,2,2,6,6-pentamethyl)-4-methyl piperidine]; PA0 (94) calcium di-[adipate of mono-(1,2,2,6,6-pentamethyl)-4-methyl piperidine]; PA0 (95) zinc di-[succinate of mono-(2,2,6,6-tetramethyl)-4-methyl piperidine]; PA0 (96) barium di-[succinate of mono-2,2,6,6-tetramethyl)-4-methyl piperidine]; PA0 (97) nickel di-[maleate of mono-(2,2,6,6-tetramethyl)-4-methyl piperidine]; PA0 (98) nickel di-[succinate of mono-(1,2,2,6,6-pentamethyl)-4-methyl piperidine]; PA0 (99) bis{[1-(2,3-epoxypropyl) 2,2,6,6-tetramethyl]-4-methyl piperidine}isophthalate; PA0 (100) bis[(1-benzyl-2,2,6,6-tetramethyl)-4-methyl piperidine]sebacate; PA0 (101) bis{[1-(-acetoxyethyl) 2,2,6,6-tetramethyl]-4-methyl piperidine}sebacate; PA0 (102) bis[(2,2,6,6-tetramethyl)-4-methyl piperidine]hexamethylene-di-carbamate; PA0 (103) bis[(2,2,6,6-tetramethyl)-4-methyl piperidine]toluene-2,4-di-carbamate; PA0 (104) bis[(2,2,6,6-tetramethyl)-4-methyl piperidine]naphthalene-1,5-di-carbamate; PA0 (105) bis[(2,2,6,6-tetramethyl)-4-methyl piperidine](oxy di-p.phenylene)di-carbamate; PA0 (106) bis[(2,2,6,6-tetramethyl)-4-methyl piperidine](methylene-di-p.phenylene)di-carbamate; PA0 (107) bis[(2,2,6,6-tetramethyl)-4-methyl piperidine](methylene-di-4,1-cyclohexylene)-di-carbamate; PA0 (108) bis[(1,2,2,6,6-pentamethyl)-4-methyl piperidine]hexamethylene-di-carbamate; PA0 (109) bis[(1,2,2,6,6-pentamethyl)-4-methyl piperidine]methylene-di-p.phenylene-di-carbamate; PA0 (110) 1,2bis[(2,2,6,6-tetramethyl)-4-piperidine methoxy]ethane; PA0 (111) 1,4bis[(2,2,6,6-tetramethyl)-4-piperidine methoxy]butane; PA0 (112) 1,4bis[(2,2,6,6-tetramethyl)-4-piperidine methoxy]butene; PA0 (113) 1,6bis[(2,2,6,6-tetramethyl)-4-piperidine methoxy]hexane; PA0 (114) 1,4bis[(2,2,6,6-tetramethyl)-4-piperidine methoxy]methylbenzene; PA0 (115) 1,3bis{[(1,2,2,6,6-pentamethyl)-4-piperidine methoxy]methyl}benzene; PA0 (116) 1,6bis{[1-(2-stearoyloxyethyl) 2,2,6,6-tetramethyl]-4-piperidine methoxy}hexane; PA0 (117) the compound: ##STR27## (118) tris[(2,2,6,6-tetramethyl)-4-methyl piperidine]trimellitate; (119) tris[(2,2,6,6-tetramethyl)-4-methyl piperidine]trimesate; PA0 (120) tris[(2,2,6,6-tetramethyl)-4-methyl piperidine]tricarballylate; PA0 (121) tris[(2,2,6,6-tetramethyl)-4-methyl piperidine]phosphite; PA0 (122) tris[(2,2,6,6-tetramethyl)-4-methyl piperidine]phosphate; PA0 (123) tris[(1,2,2,6,6-pentamethyl)-4-methyl piperidine]trimellitate; PA0 (124) tris[(1,2,2,6,6-pentamethyl)-4-methyl piperidine]phosphite; PA0 (125) tetrakis[(2,2,6,6-tetramethyl)-4-methyl piperidine]pyromellitate; PA0 (126) tetrakis[(1,2,2,6,6-pentamethyl)-4-methyl piperidine]pyromellitate; PA0 (127) (2,5-dioxa-1-phospholan-1-yloxy)-[(2,2,6,6-tetramethyl)-4-methyl piperidine]; PA0 (128) (4,4-dimethyl-2,6-dioxa-1-phospholan-1-yloxy)[(2,2,6,6-tetramethyl)-4-meth yl piperidine]; PA0 (129) O-ethyl O-[(2,2,6,6-tetramethyl)-4-methyl piperidine]benzyl phosphonate; PA0 (130) O,O'-bis[(2,2,6,6-tetramethyl)-4-methyl piperidine]phosphonate; PA0 (131) O,O'-bis[(2,2,6,6-tetramethyl)-4-methyl piperidine]benzyl phosphonate; PA0 (132) O,O'-bis-[(2,2,6,6-tetramethyl)-4-methyl piperidine]4-hydroxy-3,5-di-tertbutyl benzyl phosphonate; PA0 (133) 3,9-bis-[(2,2,6,6-tetramethyl)-4-methoxy piperidine]-2,4,8,10-tetraoxa-3,9-di-phospha-spyro[5,5]undecane.
Among the above-cited compounds, compound (1) is described in Khim. Get. Soed. 1976 No. 7, pages 927-34 (E. I. Levkoeva, L. N. Iachontov), but there is not stated that this compound is useful as stabilizer for polymers.
The derivatives of 4-hydroxy-methyl-piperidine (I) are preparable according to conventional methods by means of the processes indicated hereinbelow.
Method A
The compounds of formula (I), where Y is hydrogen, are preparable by reduction of a compound of formula (III) ##STR28## where R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are defined as hereinbefore, by means of a reducing agent such as lithium or aluminum hydride with hydrogen and a catalyst such as the nickel Raney.
Method B
The compounds of formula (I), wherein Y is an acyl group, a group obtained by removing a hydroxy group from a phosphorus-containing acid, a diacyl group, a carbonyl X group, a group obtained by removing two hydroxy groups from a phosphorus-containing acid, the group ##STR29## are obtainable by reacting a compound of formula: ##STR30## (wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are defined as hereinbefore) with a reactive derivative of the acid corresponding to group Y, for example with a halide or a lower alcohol ester.
Method C
The compounds of formula (I) in which Y represents an alkyl, alkenyl, aralkyl group, a cyclohexyl group, an alkylene group, an alkenyl group, a xylylene group, are preparable by reacting a compound of formula (IV), as already defined, with a halide of group Y.
Method D
The compounds of formula (I), wherein Y represents one of the groups --CONHR.sub.22 or --CONHR.sub.27 NH--CO--, can be prepared by reacting a compound of formula (IV), as already defined, with an isocyanate of formula R.sub.22 NCO or OCN--R.sub.27 --N--CO--C.
Method E
The compounds of formula (I), wherein Y represents one of the groups ##STR31## are preparable by reacting a compound of formula (IV), as already defined, with the carbamoyl chloride obtained by reacting phosgene on an amine of the type ##STR32##
Method F
The compound of formula (I), in which Y represents the group --CO--R.sub.20 --COOH, are preparable by reacting the compound of formula (IV), as already defined, with an anhydride of formula: ##STR33##
The esters and the salts of this group can be easily prepared according to conventional methods.
Method G
The compounds of formula (I), wherein Y represents a group ##STR34## can be prepared by reacting a compound of formula (IV), as already defined, with a compound of formula R.sub.23 --C.tbd.C--COOR.sub.24.
Method H
The compounds of formula (I), where Y represents a group ##STR35## are preparable by reacting a compound of formula (IV), as already defined, with a compound of formula: ##STR36##
When R.sub.5 is a group other than hydrogen, this can be introduced into the compound prior to or after the introduction of Y, by treating a compound of formula I, II, III or IV, where R.sub.5 is the hydrogen atom, according to one of the following methods.
Method J
The compounds of formula I, II, III or IV, in which R.sub.5 represents an alkyl group, an alkenyl group, an alkoxyalkyl group, an aralkyl group, a 2-3 epoxypropyl group, the group --CH.sub.2 --COO--R.sub.10, the group ##STR37## an aliphatic acyl group or the group --COOR.sub.13 (R.sub.10, R.sub.11, R.sub.12, R.sub.13 and R.sub.14 are the same as defined hereinbefore), are easy to prepare by reacting the corresponding compounds in which R.sub.5 is a hydrogen atom with a halide of the group R.sub.5.
Method K
The compounds of formula I, II, III or IV, in which R.sub.5 represents the group ##STR38## (R.sub.11 being defined as hereinbefore), can be prepared by reacting the corresponding compounds, in which R.sub.5 is the hydrogen atom, with an epoxide, such as ethylene oxide, propylene oxide, styrene oxide. The resulting compounds can be acylated to obtain the corresponding acylated compounds.
Method L
The compounds of formula I, II, III or IV, in which R.sub.5 represents a methyl group, are preparable according to the Leuckart-Wallach reaction, i.e., by reacting the corresponding compound, in which R.sub.5 represents the hydrogen atom, with formic acid and formaldehyde.
Method M
The compounds of formula I, II, III or IV, in which R.sub.5 represents a formyl group, can be prepared by reacting a corresponding compound, in which R.sub.5 is a hydrogen atom, with ethyl orthoformate, in the presence of acid catalyst.
The compounds of formula III, which represent the starting substances for preparing the derivatives of 4-hydroxymethyl-piperidine having general formula (I), utilized in the polymeric compositions according to the present invention, can be prepared according to the teachings of U.S. Pat. No. 4,400,513.
The derivatives of 4-hydroxy-methyl piperidine having general formula (I) are useful to stabilize polymers, in particular synthetic polymers, against photo- and thermal degradation.
Examples of polymers which can be stabilized according to the present invention are:
The proportion of 4-hydroxy-methyl-piperidine of formula (I) necessary to efficaciously stabilize the polymers depends on various factors, such as the type and properties of the polymer, the use for which it is intended, the simultaneous presence of other stabilizers.
Generally, such amounts range from 0.01 to 5% by weight of stabilizer referred to the polymer.
In particular, the preferred amount ranges from 0.02 to 1% for the polymers of olefins, dienes and styrene, from 0.02 to 0.5% for the polymers of vinyl and vinylidene, from 0.02 to 2% for polyurethanes and polyamides.
Optionally, two or more stabilizers having general formula (I) can be utilized.
The derivatives of 4-hydroxymethyl piperidine of formula (I) utilized as stabilizers in the polymeric compositions according to this invention can be easily incorporated into the polymers to be stabilized, according to conventional operating methods, e.g., the stabilizers can be mixed with the polymer in the form of a dry powder, or a stabilizer solution or suspension or emulsion can be admixed to a polymer solution or suspension or emulsion.
The derivatives of the alkyl-substituted 4-hydroxy-methyl-piperidine of formula (I) can be employed either alone or in admixture with other known additives such as antioxidants, UV-ray absorbers, pigments, fillers, basic nitrogenous polycondensates, stabilizers and the like.
Examples of such additives are oxybenzotriazoles, oxobenzophenones, Ni stabilizers, metal soaps, phenolic antioxidants, phosphites, phosphinites, thioesters, hydroquinone derivatives, triazinic compounds, acylamino-phenols, benzyl-phosphates, sterically hindered phenols such as 4,4'-bis-butylidene-bis-(2,6-di-tert.butyl-phenol); triazino-phenol compounds, etc.
Such additives can be utilized along with the compounds having formula (I), according to the present invention, in a weight ratio ranging from 0.5:1 to 3:1.
For a better understanding of the present invention and as aid to practicing the same, there are reported hereinbelow a few illustrative preferred examples which are not considered a limitation of the invention.